In general, a main air chamber for reserving compressed air is disposed within a body of a driving tool such as a nail driving machine or a screw driving machine. The main air chamber is connected to a grip. An introducing inlet connected to a compressed-air supply source is formed at a rear end of the grip. Further, at an inside of the main air chamber, there is disposed a striking cylinder which accommodates a striking piston coupled with a driver for driving a nail so as to be slidable freely. Furthermore, a head valve is provided at an upper portion of the striking cylinder. In the case where the head valve is arranged to be opened/closed with respect to the main air chamber, when the valve is opened, the compressed air within the main air chamber is supplied to the striking cylinder thereby to drive the striking piston and the driver, whereby a nail is struck and driven. After the driving, the head valve is closed to make the upper portion of the striking cylinder communicate with an exhaust path thereby to exhaust the compressed air supplied to the striking cylinder.
The driving tool would be smaller in its weight and easier in handling if the entire height thereof is lower. When the entire height of the driving tool is low, an usability of the tool is good in the case of using the tool between intermediate posts in the conventional construction method or between studs in the two-by-four method. Thus, demands for the body of the low entire height is great in such usages.
Members such as the striking cylinder, the head valve of a cylindrical shape are provided within the body. The height of the striking cylinder can not be made low since the height relates to the output of the tool. Thus, it is required to invent the position of the head valve and the structure for exhausting.
Conventionally, the head valve is disposed at the upper portion of the striking cylinder, then a cylinder cap is provided above the head valve and an exhaust cover is disposed above the cap. Thus, firstly, there has been though of a structure of exhausting to the side direction. In this case, the entire height can be made low since the exhaust cover at the upper portion is eliminated. Further, there has been though of another structure in which the head valve is disposed at the outside of the striking cylinder, as disclosed in JP-Y-06-045336. In this case, since a ratio of the height of the head valve with respect to the entire height of the body is made lower, the entire height can be further lower when combined with the aforesaid improvement of the exhausting structure.
However, according to the structure of disposing the head valve at the outside of the striking cylinder, the lower portion of the head valve is fit deeply at the outside of the striking cylinder. Thus, the top dead center of the striking piston is required to be set to a position lower than the upper end of the striking cylinder, and so the height above the striking piston is not so suppressed. Further, since the height of the head valve is lowered, it becomes necessary to provide a member for guiding and opening/closing the head valve, particularly, the lower portion thereof. Thus, to this end, conventionally another member is disposed at the inner and outer peripheries of the head valve so that another member guides the inner and outer peripheries of the head valve. Accordingly, the number of parts becomes large, which results in the increase of the weight and the cost.
An object of the invention is to provide a low entire-height structure which can reduce the number of parts to realize the low entire-height and also can reduce a cost.